Software defined network (SDN) is a networking paradigm that decouples network control and forwarding functions. The decoupling of the control plane from the data plane allows for centralization of network control, enabling effective policy administration and flexible management. The centralization of network control facilitates various network functionalities, such as network measurements, traffic engineering, enhanced quality of services, and enhanced access control. With the growing availability of SDN-enabled nodes and protocols, many organizations have started deploying SDN networks.
In a SDN, a controller computes end-to-end paths based on an abstract topology of the underlying one or more domain networks. The SDN controller may receive information to create the abstract topology from nodes and/or domain controllers within the underlying network. The abstract topology typically does not include any data related to a condition of nodes or links within the underlying network.